Contour junctions are common features of visual scenes and play a critical role in shaping our interpretation of the visual world. The goal of the experiments proposed here is to characterize the responses of neurons in the primary visual cortex to line intersections, and to understand how different aspects of intrinsic cortical circuitry may contribute to resulting patterns of cortical activation. Specifically, the proposed experiments aim to: 1) determine whether population and single-unit responses to line intersections show evidence of non-linear interactions between component stimuli, and whether these interactions produce shifts in orientation tuning similar to changes in perceived orientation that observed when lines cross 2) to understand the relationship between local cortical topography and the responses of neurons to line intersections 3) to assess the retinotopic scale over which line intersections produce non-linear responses 4) to determine the time course and underlying synaptic mechanisms of neural responses to intersections. These experiments explore the way in which line intersections are represented in V1, providing insights into the capacity of V1 to process complex stimuli, as well as their role in the conscious perception of orientation. [unreadable] [unreadable]